A typical fuel sender in an automotive fuel tank comprises a float that floats on the surface of fuel in a fuel tank. The float is typically mounted on the end of a pivot arm, which is connected to a means for providing a resistance that varies as the float moves up and down on the surface of the fuel. A resistor is typically coupled in series with the resistance means and voltage is applied across the circuit. As the resistance of the resistance means changes, the voltage across the resistance means changes. The voltage across the resistance means is used as the sender output signal and is used as an input to a fuel gauge for indicating the amount of fuel in the tank. The fuel gauge is typically a conventional air core gauge comprising at least two coils that are energized in relation to the output signal of the fuel sender. A pointer connected to a spindle of a permanent magnet rotor is rotated in relation to the energization of the coils of the air core gauge to indicate a measure of the fuel in the fuel tank.
Because motor vehicles are subject to varying accelerations due to changes in vehicle speeds and direction, fuel in the fuel tank tends to slosh unless the tank is full. Bumpy roads may also cause the fuel in the tank to slosh. Unless countermeasures are taken, fuel slosh is reflected in the fuel gauge reading as a wavering of the gauge pointer, temporarily making determination of the actual fuel level difficult for the vehicle operator.
Presently various measures are available to partially reduce the affects of fuel slosh on the fuel reading. One example is the addition of baffles to the fuel tank, increasing the cost of the tank. Another example is damping the response of the gauge with a viscous fluid, slowing the response of the gauge.
Electronic damping of the output signal of the sender can reduce the effects of fuel slosh, reducing or eliminating the requirements of baffles and viscous damping fluid. Electronic damping in the form of RC filters requires large external components due to the large required time constants. Electronic damping in the form of microprocessor implementations requires the expense of a microprocessor.